WO2005101137A1

WO2005101137A1 - Holographic recording method, holographic recorder, holographic recording/reproducing method, holographic recorder/reproducer and holographic recording medium

Info

Publication number: WO2005101137A1
Application number: PCT/JP2005/005932
Authority: WO
Inventors: Takuya Tsukagoshi; Tetsuro Mizushima; Jiro Yoshinari; Hideaki Miura
Original assignee: Tdk Corporation
Priority date: 2004-04-15
Filing date: 2005-03-29
Publication date: 2005-10-27
Also published as: JP4355607B2; JP2005301143A; US7869106B2; US20080158628A1

Abstract

There are provided a holographic recording method, a holographic recorder, a holographic recording/reproducing method, a holographic recorder/reproducer and a holographic recording medium as follows. Information is angle-multiplex-recorded as a hologram by a first format in which one of a signal light and a reference light branched from a laser light source intersects the other at a specified incident angle in a recording layer and the incident angle is altered at a specified angular pitch or a second format having a higher angle selectivity. When information is recorded in the second format having a higher angle selectivity, the incident angle can be adjusted to include such an incident angle that satisfies Bragg’s conditions at the time of recording in the first format and compatibility of reproduction can be ensured between media having different angle selectivity.

Description

Specification

Holographic recording method, holographic recording device, holographic recording / reproducing method, holographic recording / reproducing device, and holographic recording medium

Technical field

The present invention relates to a holographic recording method, a holographic recording device, a holographic recording / reproducing method, a holographic recording / reproducing device, and a holographic recording medium. Background art

As shown in FIG. 10, conventionally, as one of holographic recording methods, one of a signal light 4 and a reference light 6 obtained by branching a laser light source is applied to a predetermined layer in a recording layer 2 A of a holographic recording medium 2. A holographic recording method has been proposed in which information is angle-multiplex-recorded as a hologram by intersecting the other at an incident angle Θ and changing the incident angle Θ at a predetermined angle pitch Δ （(for example, 2003-178460 .;).

By the way, in order to improve the recording density of such a holographic recording medium 2, “thickening the recording layer” is important. Generally, the thicker the recording layer 2A of the holographic recording medium 2, the narrower the range of the incident angle satisfying the Bragg condition, and the better the angle selectivity. Specifically, as shown in FIGS. 11A and 11B, the relationship between the incident angle of the reference light 6 and the diffraction efficiency, that is, the angle selectivity differs depending on the thickness of the recording layer 2A. The medium with a thick recording layer 2A shown in FIG. 11 (A) has a smaller incident angle of the reference beam 6 that satisfies the Bragg condition than the medium with a thin recording layer 2A shown in FIG. 11 (B). The range becomes narrower and the angle selectivity increases.

[0004] As described above, if the angle selectivity is improved by increasing the thickness of the recording layer 2A, the multiplicity of recording can be increased, and the recording density can be improved. In recent years, the demand for an increase in the recording capacity of the holographic recording medium 2 has been increasing, and it is expected that the thickness of the recording layer 2A will be rapidly increased in the future.

[0005] Since simply increasing the thickness of the recording layer 2A while applying force, the condition of the incident angle changes depending on the medium, and thus the thickness of the recording layer 2A differs (angle selectivity). There is a problem that it is not possible to ensure reproduction compatibility between (different) media. Disclosure of the invention

[0006] The present invention has been made to solve such a problem, and a holographic recording method and a holographic recording method capable of ensuring reproduction compatibility between media having different angle selectivities. It is an object to provide an apparatus, a holographic recording / reproducing method, a holographic recording / reproducing apparatus, and a holographic recording medium.

[0007] As a result of earnest research, the inventor of the present invention has found that a holographic recording method, a holographic recording apparatus, a holographic recording / reproducing method, and a holographic recording method capable of ensuring reproduction compatibility between media having different angle selectivities. A graphic recording / reproducing device and a holographic recording medium were found.

[0008] That is, the above object can be achieved by the following present invention.

(1) One of the signal light and the reference light branched from the laser light source intersects the other at a predetermined incident angle on the recording layer, and changes the incident angle at a predetermined angular pitch. A holographic recording method in which information is angle-multiplexed and recorded as a hologram in a first format or a second format having a higher angle selectivity, wherein the information has a higher angle selectivity and information is recorded in a second format. A holographic recording method, characterized in that, at the time of recording, the incident angle can be adjusted so as to include an incident angle that satisfies the Bragg condition when recording in the first format.

(2) When the angle pitch at the time of recording in the first format is ΔΘ, the angle pitch at the time of recording in the second format is Δθ Zn (n is 2 or more). Holographic recording method according to the above (1), wherein:

[0011] (3) When there are a plurality of types of the angular pitches at the time of recording in the first format, the angular pitch force at the time of recording in the second format is The holographic recording method according to the above (1), characterized in that the holographic recording method includes an angular pitch that is about several times smaller than the angular pitch.

(4) The holographic recording method according to the above (3), wherein the divisor is the greatest common divisor! / ヽ.

(5) The holographic article according to (1), wherein the same information is multiplex-recorded at a plurality of incident angles near an incident angle common to the second format and the first format. Recording method.

(6) The control information on the angle selectivity, which includes at least information on the incident angle and the wavelength of the reproduction light, is recorded at an incident angle common to the second format and the first format. The holographic recording method according to any one of (1) to (5), characterized in that:

[0015] (7) One of the signal light and the reference light obtained by branching the laser light source intersects the other at a predetermined incident angle on the recording layer, and changes the incident angle at a predetermined angle pitch. A holographic recording device capable of performing angle multiplex recording of information as a hologram in a first format or a second format having a higher angle selectivity, wherein the information is stored in the second format having a higher angle selectivity. And a signal optical system and a reference optical system that can adjust the incident angle to include an incident angle that satisfies the Bragg condition when recording in the first format. Holographic recording device.

(8) When the angle pitch at the time of recording in the first format is ΔΘ, the angle pitch at the time of recording in the second format is Δθ Zn (n is 2 or more). The holographic recording device according to (7), wherein the holographic recording device is set to (integer).

(9) In the case where there are a plurality of types of the angular pitch at the time of recording in the first format, the angular pitch force at the time of recording in the second format is The holographic recording device according to the above (7), wherein the holographic recording device includes an angle pitch that is about several times smaller than the angle pitch.

[0018] (10) The horrorographic recording device according to (9), wherein the divisor is the greatest common divisor!

(11) The configuration according to (7), wherein the same information is multiplex-recorded at a plurality of incident angles near an incident angle common to the second format and the first format. Holographic recording device.

(12) A control information force related to the angle selectivity, which comprises at least information on an incident angle and a wavelength of the reproduction light, an incident angle common to the second format and the first format. The holographic recording apparatus according to any one of (7) to (11), wherein the holographic recording apparatus is capable of recording.

(13) A first format in which one of signal light and reference light branched from a laser light source intersects the other at a predetermined incident angle in a recording layer and the incident angle is changed at a predetermined angle pitch or Information is angle-multiplexed and recorded as a holo-drum in the second format having higher angle selectivity, and the recorded information is reproduced by irradiating reproduction light composed of one of the signal light and the reference light. A holographic recording / reproducing method, wherein when recording information in the second format having a high angle selectivity, the incident angle includes an incident angle satisfying a Bragg condition when recording in the first format. Control information on the angular selectivity, which is at least adjustable and includes at least information on the incident angle and the wavelength of the reproduction light, in the second format and the first format. A holographic recording / reproducing method, comprising: a step of recording at a common angle of incidence on a mat, and a step of acquiring the control information before reproducing information other than the control information. Law.

(14) The holographic recording / reproducing method according to (13), wherein the control information is obtained by associative reproduction.

(15) A first format or a first format in which one of the signal light and the reference light branched from the laser light source intersects the other at a predetermined incident angle in the recording layer and the incident angle is changed at a predetermined angle pitch. Information can be angularly multiplex-recorded as a holo-drum by the second format having higher angle selectivity, and the recorded information can be reproduced by irradiating reproduction light composed of one of the signal light and the reference light. A holographic recording / reproducing apparatus, wherein when recording information in the second format having a high angle selectivity, the incident angle includes an incident angle that satisfies a Bragg condition when recording in the first format. The control information on the angle selectivity is adjusted in the second format and the first format. A signal optical system and a reference optical system capable of recording at an incident angle common to the format, and a detection optical system capable of acquiring the control information before reproducing information other than the control information. A holographic recording / reproducing device characterized by the above-mentioned. (16) The holographic recording / reproducing apparatus according to (15), wherein the control information is acquirable by associative reproduction.

(17) A first format in which one of the signal light and the reference light obtained by branching the laser light source intersects the other at a predetermined incident angle in the recording layer, and changes the incident angle at a predetermined angle pitch or A holographic recording medium in which information is angularly multiplex-recorded as a holo-drama in a second format having a higher angle selectivity, wherein at least an incident angle common to the second format and the first format is set. A holographic recording medium, wherein the information is recorded at an incident angle that includes the holographic recording medium.

(18) When the angle pitch at the time of recording in the first format is ΔΘ, the information is recorded at an angle pitch of Δ0Zn (n is an integer of 2 or more). The holographic recording medium according to (17), wherein:

(19) In a case where there are a plurality of types of the angular pitches at the time of recording in the first format, information is recorded at an angular pitch that is approximately several powers of each of the angular pitches. The holographic recording medium according to the above (17), wherein

(20) The holographic recording medium according to (19), wherein the divisor is the greatest common divisor! / !.

(21) The holographic data according to (17), wherein the same information is multiplex-recorded at a plurality of incident angles near an incident angle common to the second format and the first format. recoding media.

[0030] (22) The control information regarding the angle selectivity, which includes at least information on the incident angle and the wavelength of the reproduction light, is recorded at an incident angle common to the second format and the first format. The holo drama recording medium according to any one of the above (17) to (21).

Brief Description of Drawings

FIG. 1 is an optical system diagram of a holographic recording device according to a first embodiment of the present invention.

FIG. 2 is a side view schematically showing a relationship between a recording layer, a reference beam, and a signal beam in the holographic recording device.

FIG. 3 is a graph showing angle selectivity of a lower format medium according to Embodiment 1 of the present invention. FIG. 4 is a graph showing the angular selectivity of the upper format medium and the lower format medium according to the first embodiment of the present invention.

FIG. 5 is a schematic diagram showing a state of angle multiplex recording of the holographic recording device according to the first embodiment of the present invention.

[Figure 6] Graph showing the angle selectivity of upper format media and lower format media with different angular pitches

FIG. 7 is a graph for explaining another recording method by the holographic recording device according to the first embodiment of the present invention.

FIG. 8 is a graph for explaining still another recording method by the holographic recording device according to the first embodiment of the present invention.

FIG. 9 is an optical system diagram of a holographic recording / reproducing apparatus according to Embodiment 2 of the present invention.

FIG. 10 is a side view schematically showing a relationship between a recording layer, a reference beam, and a signal beam in a conventional holographic recording device.

FIG. 11 is a graph showing the angle selectivity of a holographic recording medium having different recording layer thicknesses.

[0032] In the holographic recording method according to the present invention, one of the signal light and the reference light branched from the laser light source intersects the other at a predetermined incident angle in the recording layer, and the incident angle is changed at a predetermined angular pitch. A holographic recording method in which information is angularly multiplexed and recorded as a hologram in a first format or a second format having higher angle selectivity, wherein information is recorded in the second format having higher angle selectivity. In this case, the above-mentioned problem has been solved by making it possible to adjust the incident angle to include an incident angle that satisfies the Bragg condition when recording in the first format.

[0033] The "format" according to the present invention means both a physical format that specifies the recording capacity of a recording medium, a modulation method, an error correction coding method, and the like, and a logical format that specifies a recording and reproduction method. For example, a DV D-Video format, a DVD-Audio format, etc. in a DVD (Digital Versatile Disc) correspond to this.

[0034] The "first format" and the "second format" according to the present invention are different from each other only in the angle selectivity and mean the same in other physical format and logical format. The

In the following embodiments, the first format having the lower angle selectivity is expressed as “lower format”, and the second format having the higher angle selectivity is expressed as “higher format”. .

Example 1

Hereinafter, a holographic recording apparatus 10 to which the holographic recording method according to the first embodiment of the present invention is applied will be described with reference to FIG.

The holographic recording device 10 transmits a laser light source 12 and one of the linearly polarized light of the laser light from the laser light source 12, for example, a p-polarized component whose vibration plane is orthogonal, and an s-polarized component. A polarization beam splitter 14 that reflects the light, a signal optical system 18 that guides the s-polarized signal light reflected by the polarization beam splitter 14 to the holographic recording medium 16, and a p-polarized light that passes through the polarization beam splitter 14 And a reference optical system 20 whose polarization plane is rotated by about 90 degrees by the 1Z2 wavelength plate 15 and guides the reference light polarized in the s-polarized state to the holographic recording medium 16.

[0038] The signal optical system 18 includes a beam extractor composed of two first and second lenses 18A and 18B and a pinhole 18C in order to enlarge the beam diameter of the signal light emitted from the laser light source 12. A panda 18D, a mirror 18E that reflects the signal light passing through the beam expander 18D at a right angle, a spatial light modulator (hereinafter, SLM) 18F into which the signal light reflected by the mirror 18E enters, and a light passing through the SLM18F And a Fourier lens 18G for condensing the signal light into the holographic recording medium 16. The beam expander 18D forms a relay optical system by arranging the first and second lenses 18A and 18B at a distance substantially equal to the sum of the respective focal lengths. The pinhole 18C is located near the confocal point of the system, and functions as a spatial filter.

The reference optical system 20 includes two rotating mirrors 20 A and 20 B that reflect the reference light, which has also entered the polarizing beam splitter 14, in the direction of the holographic recording medium 16. The rotation mirrors 20A and 20B are supported by the rotation stages 20C and 20D so that the reflection angle can be adjusted. The angle of incidence on the recording medium 16 can be modulated. That is, angle multiplex recording is enabled.

Next, a basic principle for recording information on the holographic recording medium 16 by the holographic recording device 10 will be described.

The signal light that has entered the signal optical system 18 has its beam diameter expanded by a beam expander 18D, is reflected by a mirror 18E, is given data in the form of intensity modulation by an SLM 18F, and The light is condensed by the lens 18G and subjected to the Fourier transform of the intensity distribution, and is applied to the holographic recording medium 16.

On the other hand, the reference light that has entered the reference optical system 20 is reflected at a predetermined angle by the two rotating mirrors 20A and 20B, and then crosses with the irradiated signal light in the holographic recording medium 16. I do.

[0043] The signal light and the reference light cause optical interference in a region where the signal light and the reference light intersect, and this is recorded on the holographic recording medium 16 as a diffraction grating.

More specifically, a plurality of pieces of information are angularly multiplex-recorded on the holographic recording medium 16 through a process as described below.

First, as shown in FIG. 2 (A), a signal light is applied from a direction perpendicular to the surface of the holographic recording medium 16 and a reference light is applied to the signal light from an angle Θ. Irradiate

1

Then, both interference fringes are formed, and both interference fringes are formed.

Next, as shown in FIG. 2 (B), while keeping the incident angle of the signal light constant, the incident angle の of the reference light is changed by the angle pitch Δ 、, and the incident angle θ ( = θ + Δ))

1 2 1

Angle multiplex recording is performed on the recording layer 16A of the physical recording medium 16.

As described above, as many pieces of information as necessary are angularly multiplex-recorded while changing the incident angle of the reference light by the angle pitch ΔΘ. Note that the angle pitch Δ 設定 is set to be larger than the range of the incident angle at which the hologram can be reproduced (satisfies the Bragg condition) so that no crosstalk occurs between the information (holograms). Being done.

Next, a process of recording information on the holographic recording medium 16 by the holographic recording device 10 will be described. In the first embodiment, the lower format holographic recording medium (hereinafter, simply referred to as “lower format medium”) LM As shown in Fig. 3, the incident angle of the reference light is 0

A, 0

B, angle C at which diffraction efficiency is maximized at 0

The description will be made assuming a medium having degree selectivity.

[0049] When recording information on the holographic recording medium UM (hereinafter simply referred to as "upper format medium") of higher format having higher angle selectivity than the lower format medium LM, FIG. As shown in Fig. 5, the incident angle of the reference beam is adjusted to include the incident angles 0, 0, 0 that satisfy the Bragg condition during recording in the lower format.

A B C

Record information.

The angle pitch of the incident angle at the time of recording on the lower format medium LM is Δ 0.

L

In this case, the angle pitch Δ 0 during recording of the upper format medium UM is Δ 0 /

U L

Set to 3.

In the first embodiment, the angle pitch Δ at the time of recording the upper format medium UM is used.

に is set to 1Z3 of the angle pitch Δ 0 when recording on the lower format medium LM.

UM L

The present invention is not limited to this.If the angle pitch at the time of recording in the lower format is ΔΘ, the angle pitch at the time of recording in the upper format is Δ θ Zn (n is 2 It is preferable to set to (the above integer).

Further, in the holographic recording device 10 according to the first embodiment, the format information (control information) relating to the angle selectivity, including the information on the incident angle and the wavelength of the reproduction light, is stored in the upper format media UM and UM. Angle of incidence common to lower format media LM 0

A, 0

B, 0 C

It is now recorded in.

According to the holographic recording method according to the first embodiment, when information is recorded in the high format (second format) with high angle selectivity, the incident angle is changed to the low format (second format). When recording in (1 format), the incident angles 0, 0, 0 that satisfy the Bragg condition

A B C

Since it is possible to adjust so as to include, it is possible to ensure reproduction compatibility between media having different angle selectivities.

In particular, when the angle pitch at the time of recording in the lower format is ΔΘ, the angle pitch at the time of recording in the upper format is set to Δθ Zn (n is an integer of 2 or more). Therefore, when recording the lower format medium LM with a (higher) holographic recording device capable of reproducing the upper format medium UM, the incident angle can be easily controlled. The

The format information (control information) relating to the angle selectivity, which includes at least the information on the incident angle and the wavelength of the reproduction light, is shared by the upper format medium UM and the lower format medium LM. , 0

A B C

The compatibility of control information between the mat medium UM and the lower format medium LM can be ensured, and control during reproduction can be facilitated by information such as the incident angle and wavelength of the reproduction light.

The holographic recording method according to the present invention is not limited to the holographic recording method according to the first embodiment.

Therefore, for example, as shown in FIG. 6, when there are a plurality of types of angle pitches in the lower format medium LM2 (in this example, two types, ie, the angle pitch between the incident angles 0 and Θ)

D E

Δ force, incident angle θ, angle pitch between Θ

LM E F L

Medium Angle pitch of UM2 0 Force Lower format medium LM Angle pitch 0 (

UM L

3 Δ0 and 6 Δ0), that is, it is preferable that the angle pitch includes 3Δ0 or Δ0.In particular, the divisor 3Δ0X (tA It is preferable that the number is 3ΔΘ.

As described above, when there are a plurality of types of angular pitches at the time of recording in the lower format, the angular pitch at the time of recording in the upper format is set to include an angular pitch which is approximately several powers of each angular pitch in the lower format. In addition, it is possible to ensure reproduction compatibility between media having different angle selectivities. In particular, if the divisor is the greatest common divisor, the angle pitch can be increased and the incident angle can be correspondingly increased. Control becomes easy.

Further, as shown in FIG. 7 and FIG. 8, a plurality of incident angles 0 and 0 near the incident angle 0 (θ, Θ) common to the upper format medium UM3 (UM4) and the lower format medium LM.

A B C A1

, (0 and 0, Θ and 0), if the same information is multiplex-recorded,

A2 Bl B2 CI C2

Even if an error occurs in the incident angle when reproducing the format medium LM, it is possible to reliably reproduce the information recorded on the upper format medium UM3 (UM4). Next, a holographic recording / reproducing apparatus 30 to which the holographic recording / reproducing method according to the second embodiment of the present invention is applied will be described with reference to FIG.

The holographic recording / reproducing device 30 according to the second embodiment is obtained by adding the detection optical system 22 to the holographic recording device 10 according to the first embodiment.

[0062] The detection optical system 22 includes an imaging element 22A and an imaging lens 22B for detecting diffracted light generated when the holographic recording medium 16 is irradiated with reference light, and a signal light transmitted to the holographic recording medium 16. And an address information detector 22C for detecting angle-multiplexed diffracted light generated when the light is irradiated. The address information detector 22C can be constituted by, for example, a CCD camera or the like.

When reproducing the information of the holographic recording medium 16 recorded as in the first embodiment, the optical path of the signal optical system 18 is cut off and the holographic recording medium 16 is irradiated with only the reference light. At this time, if the reference light is irradiated under the incident angle condition corresponding to the hologram to be reproduced, the signal light is emitted as the diffracted light. Therefore, by detecting the emitted signal light with the imaging device 22A via the imaging lens 22B, the target information can be reproduced.

On the other hand, when the holographic recording medium 16 is irradiated only with the signal light by interrupting the optical path of the reference optical system 20, all the angle-multiplexed reference lights are simultaneously emitted as diffracted light. Therefore, by detecting the emitted reference light by the address information detector 22C, it is possible to simultaneously reproduce the target information angle-multiplex-recorded. Note that, in the present invention, such reproduction of the angle-multiplexed reference light is referred to as “associative reproduction”. According to this "associative reproduction", it is possible to realize an ultra-high-speed search function for instantly searching for specific data. In the holographic recording / reproducing apparatus 30 according to the second embodiment, the format information recorded on the holographic recording medium 16 is obtained by the associative reproduction.

Next, a process of reproducing information from the holographic recording medium 16 by the holographic recording / reproducing apparatus 30 will be described.

When the holographic recording medium 16 is set in the holographic recording / reproducing device 30 to be in a reproducible state, first, associative reproduction is performed to determine the incident angle and wavelength of the reproduction light. The format information in which the information is recorded is obtained. Based on this format information, reproduction control is performed, and information other than the format information is sequentially reproduced.

According to the holographic recording / reproducing apparatus according to the second embodiment, when information is recorded in the upper format (second format) having high angle selectivity, the incident angle is changed to the lower format (first format). The format information (control information) related to angle selectivity, which can be adjusted to include the incident angle that satisfies the Bragg condition during recording in the (format), and includes at least information on the incident angle and wavelength of the reproduction light, There is a process of recording at a common angle of incidence in the format (second format) and lower format (first format), and a process of acquiring format information before reproducing information other than the format information. Therefore, the control at the time of reproduction can be performed at a higher level.

In particular, since the format information (control information) is obtained by the associative reproduction, the control information can be obtained quickly, and the time until the start of the reproduction can be greatly reduced.

The holographic recording device and the holographic recording / reproducing device according to the present invention are not limited to the structure of the holographic recording device 10 and the holographic recording / reproducing device 30 according to the first and second embodiments. Absent.

[0070] Therefore, for example, while making the incident angle of the reference light constant, the incident angle of the signal light is changed by a predetermined angle pitch, and angle multiplex recording is performed on the recording layer of the holographic recording medium. Good.

Industrial potential

According to the holographic recording method, the holographic recording device, the holographic recording / reproducing method, the holographic recording / reproducing device, and the holographic recording medium of the present invention, the reproduction compatibility between media having different angle selectivities Can be secured.

Claims

The scope of the claims

[1] A first format in which one of signal light and reference light obtained by splitting a laser light source crosses the other at a predetermined incident angle on a recording layer, and the incident angle is changed at a predetermined angle pitch. This is a holographic recording method in which information is angle-multiplexed and recorded as a hologram in a second format having a higher angle selectivity. When recording information in the second format having a high angle selectivity, A holographic recording method, characterized in that the incident angle can be adjusted so as to include an incident angle that satisfies the Bragg condition at the time of recording in the first format.

[2] In claim 1,

When the angle pitch during recording in the first format is ΔΘ, the angle pitch during recording in the second format is set to Δθ Zn (n is an integer of 2 or more). A holographic recording method characterized by the following.

[3] In claim 1,

When there are a plurality of types of the angular pitches at the time of recording in the first format, the angular pitch at the time of recording in the second format may be smaller than that of the respective angular pitches in the first format. A holographic recording method characterized by including an angular pitch.

[4] In claim 3,

A holographic recording method, wherein the divisor is a greatest common divisor.

[5] In claim 1,

A holographic recording method, wherein the same information is multiplex-recorded at a plurality of incident angles near an incident angle common to the second format and the first format.

[6] In any one of claims 1 to 5,

The control information on the angle selectivity, which includes at least information on the incident angle and the wavelength of the reproduction light, is recorded at an incident angle common to the second format and the first format. Holographic recording method.

[7] A first format in which one of a signal light and a reference light branched from a laser light source intersects the other at a predetermined incident angle on a recording layer, and the incident angle is changed at a predetermined angle pitch. Alternatively, there is provided a holographic recording apparatus capable of performing angle multiplex recording of information as a hologram in a second format having a higher angle selectivity, wherein the information is recorded in the second format having a higher angle selectivity. When recording the incident angle in the first format! A holographic recording apparatus comprising a signal optical system and a reference optical system that can be adjusted to include an incident angle that satisfies the Bragg condition.

[8] In claim 7,

When the angle pitch during recording in the first format is ΔΘ, the angle pitch during recording in the second format is set to Δθ Zn (n is an integer of 2 or more). A holographic recording device.

[9] In claim 7,

When there are a plurality of types of the angular pitches at the time of recording in the first format, the angle pitch at the time of recording in the second format is about A holographic recording device characterized by including an angular pitch.

[10] In claim 9,

The holographic recording device, wherein the divisor is a greatest common divisor.

[11] In claim 7,

A holographic recording apparatus, wherein the same information is multiplex-recorded at a plurality of incident angles near an incident angle common to the second format and the first format.

[12] In any one of claims 7 to 11,

The control information regarding the angle selectivity, which includes at least information on the incident angle and the wavelength of the reproduction light. It is assumed that recording can be performed at an incident angle common to the second format and the first format. Features holographic recording device.

[13] A first format in which one of the signal light and the reference light obtained by branching the laser light source intersects the other at a predetermined incident angle in the recording layer and changes the incident angle at a predetermined angle pitch or an angle larger than this Information is angle-multiplexed and recorded as a hologram in the second format having high selectivity, and a reproduction light composed of one of the signal light and the reference light is irradiated. A holographic recording / reproducing method for reproducing the recorded information, wherein, when recording information in the second format having a high angle selectivity, recording the incident angle in the first format. Sometimes, the control information on the angle selectivity, which can be adjusted to include the incident angle satisfying the Bragg condition, and includes at least the information on the incident angle and the wavelength of the reproduction light, is transmitted in the second format and Holographic recording / reproduction, comprising: recording at a common incident angle in the first format; and acquiring the control information before reproducing information other than the control information. Method.

[14] In claim 13,

A holographic recording / reproducing method, wherein the control information is obtained by associative reproduction.

[15] A first format in which one of the signal light and the reference light branched from the laser light source intersects the other at a predetermined incident angle in the recording layer, and changes the incident angle at a predetermined angle pitch or an angle larger than this. Holographic recording / reproduction capable of performing angle multiplex recording of information as a hologram in a second format having high selectivity and reproducing the information recorded by irradiating reproduction light composed of one of the signal light and the reference light An apparatus for recording information in the second format having high angle selectivity, wherein the incident angle is adjusted to include an incident angle satisfying a Bragg condition when recording in the first format. Control information on the angle selectivity, which is at least capable of including information on the incident angle and the wavelength of the reproduction light, is stored in the second format and the first format. A signal optical system and a reference optical system capable of recording at a common angle of incidence on a mat, and a detection optical system capable of acquiring the control information before reproducing information other than the control information. A holographic recording / reproducing device characterized by this.

[16] In claim 15,

The holo drama recording / reproducing apparatus, wherein the control information can be obtained by associative reproduction.

[17] A first format in which one of the signal light and the reference light branched from the laser light source intersects the other at a predetermined incident angle on the recording layer and changes the incident angle at a predetermined angle pitch or an angle larger than this. A second, highly selective format allows information to be A holographic recording medium on which angle multiplex recording has been performed, wherein the information is recorded at an incident angle including at least an incident angle common to the second format and the first format. Holographic recording medium.

[18] In claim 17,

Holographically, wherein, when the angular pitch during recording in the first format is Δ フォーマット, the information is recorded at an angular pitch of Δθ Zn (n is an integer of 2 or more). recoding media.

[19] In claim 17,

When there are a plurality of types of the angular pitch at the time of recording in the first format,

A holographic recording medium characterized in that information is recorded at an angular pitch that is approximately several powers of each of the angular pitches.

[20] In claim 19,

A holographic recording medium, wherein the divisor is a greatest common divisor.

[21] In claim 17,

A holographic recording medium, wherein the same information is multiplex-recorded at a plurality of incident angles near an incident angle common to the second format and the first format.

[22] In any one of claims 17 to 21,

Control information regarding the angle selectivity, which includes at least information on the incident angle and wavelength of the reproduction light, is recorded at a common incident angle in the second format and the first format. Holographic recording medium.